Paper - Elasmobranch captures in the Fijian pelagic longline fishery

Good paper by Susanna about the shark fisheries by the Fijian pelagic longline industry, updated and revised early 2016.

Elasmobranch captures in the Fijian pelagic longline fishery

Susanna Piovanoa, The University of the South Pacific, Suva, Fiji
Eric Gilman, Hawaii Pacific University, Honolulu, USA

Abstract

1. Pelagic longline fisheries for relatively fecund tuna and tuna-like species can have large adverse effects on incidentally caught species with low-fecundity, including elasmobranchs.

2. Analyses of observer programme data from the Fiji longline fishery from 2011 to 2014 were conducted to characterize the shark and ray catch composition and identify factors that significantly explained standardized catch rates. Catch data were fitted to generalized linear models to identify potentially significant explanatory variables.

3. With a nominal catch rate of 0.610 elasmobranchs per 1000 hooks, a total of 27 species of elasmobranchs were captured, 48% of which are categorized as Threatened under the IUCN Red List. Sharks and rays made up 2.4% and 1.4%, respectively, of total fish catch. Blue sharks and pelagic stingrays accounted for 51% and 99% of caught sharks and rays, respectively.

4. There was near elimination of ‘shark lines’, branchlines set at or near the sea surface via attachment directly to floats, after 2011.

5. Of caught elasmobranchs, 35% were finned, 11% had the entire carcass retained, and the remainder was released alive or discarded dead. Finning of elasmobranchs listed in CITES Appendix II was not observed in 2014.

6. There were significantly higher standardized shark and ray catch rates on narrower J-shaped hooks than on wider circle hooks. Based on findings from previous studies on single factor effects of hook width and shape, the smaller minimum width of the J-shaped hooks may have caused the higher shark and ray catch rates. For sharks, the effect of hook width may have exceeded the effect of hook shape, where small increases in shark catch rates have been observed on circle vs J-shaped hooks.

7. Shark and ray standardized catch rates were lowest in the latter half of the year. Focusing effort during the second half of the year could reduce elasmobranch catch rates.

Received 19 November 2015; Revised 04 March 2016; Accepted 25 March 2016

KEY WORDS : conservation evaluation; endangered species; fish; fishing; ocean; protected species

Download pdf here. Elasmobranch captures in the Fijian pelagic longline fishery – 2016_Piovano Gilman-Aq Conserv Elasmo LL bycatch Fiji

Aquatic Conservation: Marine And Freshwater Ecosystems

Published in : Aquatic Conserv: Mar. Freshw. Ecosyst. (2016)
Published online in Wiley Online Library
(wileyonlinelibrary.com). DOI: 10.1002/aqc.2666
Edited By: Professor Philip J. Boon and Professor John M. Baxter
Impact Factor: 2.415
ISI Journal Citation Reports © Ranking: 2015: 13/85 (Water Resources); 19/103 (Marine & Freshwater Biology); 75/225 (Environmental Sciences)
Online ISSN: 1099-0755

Throughout the months of April and November every year, you have the opportunity to help celebrate and record Fiji’s amazing coral reef biodiversity, show you care about our world’s delicate coral reef systems, and have fun, by taking part in the FIJI-WIDE SHARK COUNT!

Easy to do, this is suitable for visitors and locals alike, whether you like to fish, snorkel, or SCUBA dive. We hope that tourists, school children, scientists and all people with an interest in the marine environment will take to the reefs with us to search for the Sharks of Fiji!

The Great Fiji Shark Count will be held across Fiji every April and November every year.

You can do a single count, or take part as many times as you like during that month, so that you cover different reefs. All data will be gratefully accepted!

So, see your resort, watersports operator or travel agent, get your Shark identification materials and dive into the beautiful blue waters of Fiji, to be a part of history!